Fluid diode



Dec. 2, 1969 R. w. HATCH, JR 3,481,353

FLUID DIODE Filed May 8, 196'? FIG. I

FIG. 2

INVENTOR.

RICHARD W. HATCH JR Dam-J 5 ATTORNEY United States Patent US. Cl.13781.5 1 Claim ABSTRACT or THE DISCLOSURE Two tubes preferablyprojecting laminar flow are disposed with an obtuse angle between theircenter lines and in a manner so that the projected flow from a firsttube does not intercept the terminating orifice of the second tube,while the projected flow from the second tube does closely intercept theterminating orifice of the first tube; with this arrangement a fluidrectification phenomena is observed, in which a fluid supplied throughthe first tube has no affect upon the second tube, while a fluidsupplied through second tube will produce a responsive pressure effectin the first tube.

This invention relates to fluid logic, and more particularly to a fluiddiode element which may be used generally in fluid logic applications.

In the fluidic field, specific devices have been developed to performfunctions analogous to those performed by electrical circuits. Amongfluidic developments include various forms of amplifiers, switches,fluidic restrictions and resistances, fluidic capacitances, and resonantcircuits. A diode element has been in use which is the vortex diode. Inthe vortex diode one direction of stream is tangentially with a chamberwhile the other stream is centrally in the chamber normal to the vortex.Reverse flow in which the fluid input is provided to the chamber centermeets with a higher fluidic resistance than with the fluid suppliedtangentially to the chamber. The vortex diode is somewhat bulky, anddoes not have too high a forward-reverse ratio.

Inasmuch as it is desirable to be able to incorporate all the fluidicanalogs of electrical circuits into fluidic circuits, it would beconvenient to have available a fluidic diode which is very simple inconstruction, inexpensive to manufacture, while exhibiting thecharacteristics of a good forward-reverse ratio so as to be readilyemployed as an element in a fluidic circuit.

The present invention provides a fluidic diode element having a highsignal transfer in the forward direction, with an extremely low signaltransfer in the backward direction. The fluidic device of the presentinvention is quite simple, consisting of a pair of tubes arranged in afashion so that the projected stream of one tube interferes in noappreciable way with the termination of a second tube, while theprojected stream from the second tube is directed at the orificetermination of the first tube so that the first tube responds to thefluid projected by the second tube. This arrangement is extremelysimple, and performs the function of a fluidic diode element veryacceptably with much less complication than fluid diode elements of theprior art.

These and other advantages of the invention will be in part apparentfrom the following sepcification and in part from the accompanyingfigures in which:

FIGURE 1 is a cross-sectional schematic diagram illustrating the mutualpositions of the pair of tubes comprising the fluidic diode elements.

FIGURE 2 is a cross-sectional schematic of the fluidic diode of theinvention illustrating beveled tube terminaice tions to more effectivelyfacilitate the functions of the diode element.

Referring to FIGURE 1, tube 12 is shown with termination 13 thereofclosely proximate termination 15 of tube 16. Tubes 12 and 16 aredisposed with an obtuse angle theta between center line 14 of tube 12and center line 18 of tube 16. In addition, the projected diameter 19-20of tube 12 is clear of termination 15, or any part, of tube 16; theprojected diameter 21-22 of tube 16 is disposed to achieve as completean interception of termination 13 of tube 12 as may be practical. Thismutual disposition of tubes Hand 16 may be effected by a convenientprovision of an angle theta therebetween preferably in the range of-160, an angle theta of being found convenient and suitable.

It is convenient in the practice of this invention to provide forsufficient lengths of tubes 12 and 16, up to their respectiveterminations 13 and 15 thereof to provide for laminar projections fromeach tube when a source of supply is furnished. That is, the length oftube 12 from termination 13 thereof to a point 11 back in tube 12 shouldbe sufficient in terms of the Reynolds number of the fluid contemplatedfor the application to provide for laminar flow; similarly, a distancebetween termination 15 and point 17 of tube 16 should be provided toinsure laminar flow projection from tube 16 at times a source of supplyis furnished back from point 17 thereof.

With this configuration, a provision of fluidic pressure in a directionfrom point 11 to termination 13 of tube 12 will result in a laminarprojection of a fluid stream closely in a line with the projectiondiameter 19-20 of tube 12. As is illustrated in FIGURE 1, the projecteddiameter 19-20 does not interfere With termination 15 of tube 16. Inpractice, tube 16, and particularly any part of termination 15 thereof,should be off-set sufliciently from projected diameter 19-20 to insure aminimum interaction at times tube 12 is projecting a laminar stream. Thecondition of projected laminar flow from tube 12 may be termed thereverse direction condition of the fluidic diode, in that no appreciableeffect will be transferred to tube 16 in this reverse condition.

In the forward condition of the fluidic diode, a source of supply isfurnished to tube 16 from point 17, thereby projecting a laminar flowfrom termination 15 along projected diameter 21-22 of tube 16. Theprojected flow from tube strikes the cross-sectional area of termination13 of tube 12 at an angle which is suflicient to cause a responsivepressure build-up in tube 12. This pressure build-up may be sensed byappropriate fluidic apparatus connected back of point 11 of tube 12. Fora strong response in tube 12, the termination 13 of tube 12 should bedisposed as completely as possible within the projected flow from tube16. In this disposition, projected center line 18 of tube 16 willintercept center line 14 of tube 12 approximately where center line 14crosses through the plane of termination 13.

Referring to FIGURE 2, termination 13 of tube 12 is shown with a bevelso that the plane of termination 13 more nearly is a right angle toprojected center line 18 of tube 16. In addition, termination 15 of tube16 is shown beveled so that the complete termination 15 of tube 16 maymore closely approach projected diameter 19-20 of tube 12, withoutappreciably increasing any interaction in the reverse direction offluidic element operation. By so beveling terminations 13 and 15 aredescribed, the open area which must be allowed for between terminations13 and 15 is considerably reduced, thereby improving the performance ofthe fluidic diode in the forward direction, transferring a higherpressure response to tube 12 thereof. The provision of beveling will notappreciably detract from the isolation function of the fluidic diodeelement in the reverse condition thereof.

What is claimed is:

1. A fluidic diode element having a first tube adapted to project alaminar fluidic How and a second tube adapted to project a laminarfluidic flow arranged with an obtuse angle of approximately 150 betweentheir respective projected center lines and in a manner so thatprojected flow from said first tube does not intercept the terminationof said second tube while projected flow from said second tubeintercepts the termination of said first tube, with the respectivetermination of said first and second tubes being bevelled to allow areduction in the spacing between said respective terminations whilepreserving non-interaction in the reverse condition of flow wherein astream is projected from said first tube and enhancing forward inter-References Cited C. L. Stong, The Amateur Scientist, How Streams ofWater Can Be Used to Create Analogues of Electronic Tubes and Circuitsin Scientific American, vol. 207, No. 2, August 1962, pp. 128438.

M. CARY NELSON, Primary Examiner W. R. CLINE, Assistant Examiner

